Romney calls Arizona immigration law a model for the nation

Mitt Romney called the controversial Arizona illegal immigration law a model for the country, and blasted the Obama administration for challenging it in court.

"I will drop those lawsuits on Day One," Romney said in response to a question on illegal immigration during a GOP candidate debate in Mesa, Ariz. Gov. Jan Brewer, who signed the bill, was in the audience.

"I'll also complete the fence, I'll make sure we have enough Border Patrol agents to secure the fence, and I will make sure we have an E-Verify system and require employers to check the documents of workers," he added.

Rick Santorum praised Maricopa County Sheriff Joe Arpaio for a tough stance on illegal immigration, and said he would support local law enforcement efforts to tackle the challenges it posed.

Newt Gingrich defended his past support for a comprehensive approach to illegal immigration, and said if elected he would "go one step at a time" -- starting with securing the border.

Gingrich otherwise declined to respond directly to concerns by Sen. Marco Rubio of Florida and others that Republicans have risked harming the party among Latinos with their hard-line stances.

Ron Paul joked in his answer about the need to "forget about the border between Pakistan and Afghanistan and deal with our border."